1. Field of the Invention
The present invention relates to an inkjet recording method and an inkjet recording apparatus, and more particularly to an inkjet recording method and an inkjet recording apparatus for forming an image by depositing treatment liquid onto a recording medium and then depositing ink.
2. Description of the Related Art
An inkjet recording apparatus is able to record images of good quality by means of a simple composition, and therefore such apparatuses are widely used as domestic printers for individual use and office printers for commercial use. In the case of office printers for commercial use, in particular, there are increasing demands for higher processing speed and higher image quality.
One known system for carrying out inkjet recording at high speed is a system in which ink is deposited in a single pass method by a page-wide line head. Although this system is capable of high recording speed, it has a problem in that there is little time difference between the landing of adjacent dots and therefore interference (bleeding) between the dots is liable to occur and it is difficult to carry out recording of high definition. Furthermore, if printing onto normal paper (non-coated paper), since the coloring material in the ink permeates deeply into the paper, then there is also a problem in that the image density and the image resolution decline.
As a method for resolving these problems, a method is known in which a treatment liquid is deposited before depositing ink and this treatment liquid is caused to react with the ink. For example, a method is known in which, by depositing a treatment liquid containing an acidic aggregating agent and then depositing pigment particles as a coloring material, the Coulomb repulsion of the pigment particles is neutralized, the particles are caused to aggregate, and the viscosity of the ink liquid is raised (see Japanese Patent Application Publication Nos. 2004-010633 and 2007-161753). According to this method, it is possible to suppress interference between the dots, and it is possible to record with high definition and no density non-uniformities. Moreover, by suppressing permeation of the coloring material of the ink into the paper, it is possible to obtain high image density.
This method has chiefly been developed with the object of printing onto normal paper, and in recent years, there have been demands for printing onto coated printing paper, with the object of printing with higher quality. However, if printing onto coated paper, the print quality varies greatly depending on the deposition conditions of the treatment liquid. For example, if the amount of aggregating agent present on the surface of the paper is excessively large, then the spread of the ink dots formed by the deposited ink droplets is suppressed and there is a problem in that it is not possible to form a solid image. Furthermore, if using an acidic aggregating agent, yellowing of the paper occurs when the amount of aggregating agent permeating into the base paper layer is excessively large.
In order to resolve these problems, various methods have been proposed. For example, Japanese Patent Application Publication No. 2000-037942 discloses heating and pressing the medium after depositing treatment liquid, thereby a large amount of aggregating agent is left on the surface of the paper and the reaction efficiency is thus improved, while wrinkles in the paper is suppressed. Japanese Patent Application Publication No. 2002-079739 discloses leaving a large amount of aggregating agent on the surface of the paper, thereby improving the reaction efficiency, by using a treatment liquid of high viscosity. Japanese Patent Application Publication No. 2006-315206 discloses stabilizing the state of the treatment liquid and stabilizing the image quality, by providing a device for adjusting the permeated volume, permeability and deposition volume of the treatment liquid.
However, none of the related documents describes specifically in what state the droplets of ink should be deposited. In the related art, if droplets of ink are deposited after depositing treatment liquid onto a coated paper, then there are possible problems, such as reduced diameter of the ink dots, decline in glossiness, landing interference (decline of image resolution), and extended drying time.